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REDUCTION OF RADIATION DOSE OF 320-ROW CORONARY COMPUTED TOMOGRAPHY ANGIOGRAPHY THROUGH PRIOR CORONARY CALCIUM SCANNING
A67.E627 JACC March 9, 2010 Volume 55, issue 10A
IMAGING AND DIAGNOSTIC TESTING REDUCTION OF RADIATION DOSE OF 320-ROW CORONARY COMPUTED TOMOGRAPHY ANGIOGRAPHY THROUGH PRIOR CORONARY CALCIUM SCANNING ACC Poster Contributions Georgia World Congress Center, Hall B5 Sunday, March 14, 2010, 9:30 a.m.-10:30 a.m.
Session Title: CT Coronary Angiography: Radiation Exposure and Special Uses Abstract Category: CT Coronary Angiography Presentation Number: 1033-189 Authors: Marc Dewey, Elke Zimmermann, Ulrike Wollenberg, Matthias Rief, Johannes Greupner, Bernd Hamm, Charité, Berlin, Germany Background: Computed tomography angiography (CTA) of the coronary arteries allows reliable detection of coronary arteries stenoses but involves considerable radiation exposure. 320-row CT covering up to 16 cm, can scan the whole heart in one rotation. However, most hearts are smaller than 16 cm. Individual heart sizes can be determined on a noncontrast coronary artery calcium scan (CACS). Such a low-dose CACS may be used to individually adjust the CTA scanning range in order to reduce the total radiation dose. Methods: Forty patients with suspected coronary artery disease (10 women, 30 men, median 60 years of age) underwent coronary CT using a 320row scanner (Aquilion ONE, Toshiba; 0.35 s gantry rotation time). Prior to CTA a noncontrast low-dose CACS with 16-cm scan range was performed (120 kV, 150 mA) to adjust the Z-axis scan range of the subsequent coronary CTA in order to reduce the radiation dose. The subsequent coronary CTA (120 kV, 350-450 mA) used the individual heart size (+ 1 cm above and below) as the scan range. The total radiation dose of CACS and CTA was compared with the calculated radiation exposure of a sole unadjusted 16-cm wide CTA. Results: The adjusted CTA scan range was 12 cm in 39 patients and 12.8 cm in 1 patient. On average the effective dose of CACS plus the adjusted CTA was significantly lower than the calculated exposure for an unadjusted 16-cm 320-row CTA (9.0±5.4 mSv vs. 9.9±7.1 mSv, p< 0.05). The benefit of radiation reduction was even greater when 2 or 3 heart beats were used for CTA (n=9; 17.1±6.6 mSv vs. 20.6±8.7mSv; p=0.001) as compared with single-heart beat CTAs (6.7±1.2mSv vs. 6.8±1.3mSv). Conclusions: 320-row coronary CTA with individually adjusted scan range significantly reduces radiation exposure compared with unadjusted whole-range 16-cm CTA. The benefit is most pronounced for patients with higher heart rates (>65/min). Obtaining a noncontrast coronary artery calcium scan prior to 320-row CTA to determine the exact anatomic extent of the coronary arteries is recommended for overall dose reduction while it also has the advantage of being able to calculate the individual coronary calcium score.
IMAGING AND DIAGNOSTIC TESTING REDUCTION OF RADIATION DOSE OF 320-ROW CORONARY COMPUTED TOMOGRAPHY ANGIOGRAPHY THROUGH PRIOR CORONARY CALCIUM SCANNING ACC Poster Contributions Georgia World Congress Center, Hall B5 Sunday, March 14, 2010, 9:30 a.m.-10:30 a.m.
Session Title: CT Coronary Angiography: Radiation Exposure and Special Uses Abstract Category: CT Coronary Angiography Presentation Number: 1033-189 Authors: Marc Dewey, Elke Zimmermann, Ulrike Wollenberg, Matthias Rief, Johannes Greupner, Bernd Hamm, Charité, Berlin, Germany Background: Computed tomography angiography (CTA) of the coronary arteries allows reliable detection of coronary arteries stenoses but involves considerable radiation exposure. 320-row CT covering up to 16 cm, can scan the whole heart in one rotation. However, most hearts are smaller than 16 cm. Individual heart sizes can be determined on a noncontrast coronary artery calcium scan (CACS). Such a low-dose CACS may be used to individually adjust the CTA scanning range in order to reduce the total radiation dose. Methods: Forty patients with suspected coronary artery disease (10 women, 30 men, median 60 years of age) underwent coronary CT using a 320row scanner (Aquilion ONE, Toshiba; 0.35 s gantry rotation time). Prior to CTA a noncontrast low-dose CACS with 16-cm scan range was performed (120 kV, 150 mA) to adjust the Z-axis scan range of the subsequent coronary CTA in order to reduce the radiation dose. The subsequent coronary CTA (120 kV, 350-450 mA) used the individual heart size (+ 1 cm above and below) as the scan range. The total radiation dose of CACS and CTA was compared with the calculated radiation exposure of a sole unadjusted 16-cm wide CTA. Results: The adjusted CTA scan range was 12 cm in 39 patients and 12.8 cm in 1 patient. On average the effective dose of CACS plus the adjusted CTA was significantly lower than the calculated exposure for an unadjusted 16-cm 320-row CTA (9.0±5.4 mSv vs. 9.9±7.1 mSv, p< 0.05). The benefit of radiation reduction was even greater when 2 or 3 heart beats were used for CTA (n=9; 17.1±6.6 mSv vs. 20.6±8.7mSv; p=0.001) as compared with single-heart beat CTAs (6.7±1.2mSv vs. 6.8±1.3mSv). Conclusions: 320-row coronary CTA with individually adjusted scan range significantly reduces radiation exposure compared with unadjusted whole-range 16-cm CTA. The benefit is most pronounced for patients with higher heart rates (>65/min). Obtaining a noncontrast coronary artery calcium scan prior to 320-row CTA to determine the exact anatomic extent of the coronary arteries is recommended for overall dose reduction while it also has the advantage of being able to calculate the individual coronary calcium score.